As the optical requirements applied to objective lenses increase, the mechanical tolerances required during the manufacture of such objectives also increase. This increasingly leads to difficulties.
Thus for example, in the case of objectives with a correction function, a sleeve is often provided which can be formed as a hollow cylinder, in which a first positioning member is housed displaceable in longitudinal direction of the sleeve, wherein the first positioning member holds at least one lens. In order to ensure displaceability, in the case for example of a positioning member with a diameter of 20 mm and a height of 15 mm, an average base clearance of 0.004 mm is provided between the positioning member and the sleeve. As the positioning member is often connected to a drive-side pin and is entrained by same in order to be moved, the positioning member can tilt in the sleeve, which results in an undesired lateral offset of the at least one lens of the positioning member. Tilting can also occur if the objective is rotated in order to be moved from an inverse into an upright operating position.